Spinel/perovskite cobaltite nanocomposites synthesized by combinatorial pulsed laser deposition

Abstract

Perovskite/spinel nanocomposites have attracted great attention due to the novel properties that originate from the coupling between two oxides through their interfaces. Combinatorial pulsed laser deposition was used in this work to grow La_0.8Sr_0.2CoO₃ (LSC)/CoFe₂O₄ (CFO) nanocomposites on (001) SrTiO₃ (STO) under various growth conditions. At a substrate temperature of 680 °C, the LSC/CFO consisted of columns of CFO and a third phase, likely to be CoO_x, within a highly textured LSC matrix. Lowering the temperature to 600 °C resulted in highly textured LSC/CFO nanocomposites consisting of grains of LSC and CFO a few nanometers in diameter. The grain size increased with decreasing growth rate. In the nanocomposites, redistribution of Fe into the perovskite phase is expected. The strain in the CFO was impacted by the lattice match at the interfaces with the LSC, and changes in composition as well as the strain led to lower magnetic anisotropy compared with CFO films on STO. This approach can also be used to produce other novel nanocrystalline spinel/perovskite systems.